For 25 years my sister taught a CHP class on how to understand and apply the DMV laws and enforce them..... she traveled the state and often had the same CHP officers from one year to the next in the class... . her comments is that most of the officers don't know their "blank, blank, blank" to save their a**'s..... the commerical officer is the guy you need to find... .
BTW she also said that most of the clerks in the DMV offices shouldn't be trying to tell you either... . their just clerks pushing paper.....
I know this isn't an answer... . but I drive through CA all the time with a WA licence. . and always wonder what's going to happen when I get stopped... . I always pull a heavy trailer.....
Throttle Jockey... . I've had the same kind of stop, never bothered to check my licence, or the weight of the trailer,,, lets see, your cab card, insurance, log book, etc etc... .